Air chamber assembly

ABSTRACT

An air chamber assembly including two adjacently disposed fluorescent lighting units mounted in the ceiling of, for example, a commercial office or school, the assembly comprising an air chamber which is located within a space between the two lighting units and which is defined by a hollow air chamber casing, or air boot. The casing is formed with a ventilation air inlet duct through which air having the desired temperature and humidity may be supplied to the interior of the casing from a suitably located source of such air within the associated building. The assembly also comprises a support beam which is of inverted channel form in cross-section and which has a web portion, depending parallel limb portions, and outwardly directed flange portions projecting from the longitudinal edges of the limb portions of the beam remote from the web portion in a plane parallel to the plane containing the web portion. In certain embodiments of the invention, heat-fusible plates, rods or bodies are disposed between the web portion or the flange portions of the beam and the air chamber casing, thereby to maintain an edge portion of the casing a pre-determined spaced distance from the beam. In an alternative embodiment of the invention, heat-fusible strips are provided, each strip being secured to a portion of the casing which is pivotally mounted relative to the remainder of the casing, and to said remainder of the casing. Movement of the pivotal portions of the casing is thus prevented except on fusion of the heat-fusible strips, the pivotal portions of the casing each having an edge which is disposed in supported contact with the beam to maintain the above-mentioned edge portion of the casing at said pre-determined distance from the beam except on pivotal movement of the pivotal portions of the casing. The predetermined spaced distance between the above-mentioned edge portion of the casing and the beam defines a ventilation air outlet duct through which ventilation air may flow from the interior of the casing to the room space or the like below the assembly, the casing being urged under gravity in the downward direction to cause this edge portion of the casing to enter into air-tight sealing contact with the flange portions of the beam on fusion of the heat-fusible plates, rods, bodies or strips.

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A L N I: 6 673 and outwardly directed flange portions projecting fromthe [2H pp 0 longitudinal edges of the limb portions of the beam remotefrom the web portion in a plane parallel to the plane containing the webportion. In certain embodiments of the invention, heat-fusible plates,rods or bodies are disposed between the web portion or the flangeportions of the beam and the air chamber casing, thereby to maintain anedge portion of the casing a pre-determined spaced distance from thebeam. In an alternative embodiment of the invention, heat-fusible stripsare provided each strip being secured to a portion of the eas-References Cited ing which is pivotally mounted relative to theremainder of the casing, and to said remainder of the casing. Movementof the pivotal portions of the casing is thus prevented except on fu-UNITED STATES PATENTS Maranville..... Kasch.........

Lazerson.

ing. The re-determined spaced distance between the abovementioned edgeportion of the casing and the beam defines a Baker ventilation airoutlet duct through which ventilation air may flow from the interior ofthe casing to the room space or the like below the assembly, the casingbeing urged under gravity in the downward direction to cause this edgeportion of the casing to enter into air-tight sealing contact with theflange portions of the beam on fusion of the heat-fusible plates, rods,bodies or strips.

Primary Examiner-William E. Wayner Atlorney*Maybee & Legris [57]ABSTRACT An air chamber assembly including two adjacently disposedfluorescent lighting units mounted in the ceiling of, for example, acommercial office or school, the assembly comprising an air chamberwhich is located within a space between the 17 Claims, 10 DrawingFigures Patented May 30, 1972 3,665,838

4 Sheets-Sheet 1 INVENIUR.

CHARLES G. SHEPHERD ATTORNEYS Patented May 30, 1972 3,665,838

4 Sheets-Sheet 2 I N VEN TOR.

CHARLES G. SHEPHERD ATTORNEYS Patented May 30, 1972 3,665,838

4 Sheets-Sheet 3 I N VIL'N'I CHARLES G. SHEPHERD ATTORNEYS Patented May30, 1972 4 Sheets-Sheet 4 FIG. 9

FIG. 'IO INVEN'IUR.

CHARLES G. SHEPHERD ATTORNEYS AIR CHAMBER ASSEMBLY This invention isconcerned with an air chamber assembly which includes a hollow airchamber casing to which ventilation air may operatively be supplied froma convenient source thereof, and from which the ventilation air may, inturn, be supplied to the room space or the like disposed below theassembly, the air chamber defined by the casing being particularly,although not exclusively, intended to be disposed between adjacentlighting units in the ceiling of a building, such as a commercial officeor school.

It is a disadvantage of such an assembly that if a fire should occur inthe room space or the like below the assembly the fire may rapidlyspread to other room spaces or the like within the building, suchspreading of the fire occuring through the ventilation air outlet fromthe air chamber, the ventilation air inlet to the chamber and theducting which connects the ventilation air inlets of the various airchamber assemblies within the building to the source of ventilation air.Clearly, it is desirable to ensure that, if a fire should occur within aroom space or the like in a building, the fire is isolated within theroom space or the like in question and does not spread to the remainingroom spaces or the like in the building. With the view to achieving thisdesirable result, it has hitherto been proposed to provide theventilation air outlet from each air chamber with a valve mechanism,such as a butterfly type valve, which automatically closes when thetemperature within the room space below the assembly rises to apre-determined value, but while such valve mechanisms have operatedreasonably satisfactorily they are relatively complex and expensive and,for this reason, their use has only been on a very limited scale.

Fairly simple arrangements by means of which an opening or duct may beclosed when the temperature to which the arrangement are subjected risesto a pre-determined value, the passage of fire through the opening orduct thereby being prevented, are known. The most relevant sucharrangements of which the inventor is aware are those disclosed in US.Pat. Nos. 997,481 which issued on July 11, l9ll to G. Walker et al.;2,580,540 which issued on Jan. I, 1952 to C.R. Graves and 3,341,971which issued on Sept. 19, 1967 to GP. Hartman, Jr. Thus, in theconstructions disclosed in these patents the openings or ducts throughwhich fire could pass are operatively closed by the fire proof doors ofWalker, the slab of Graves or the damper blades 24 of Hartman, J r., theoperation of these members being initiated by the melting of aheat-fusible element or elements. 7

It will be noted, however, that these members which operatively serve toclose the openings or ducts in the constructions disclosed in theabove-numbered patents serve no purpose until the heat-fusible elementor elements melt. Thus, the members in question are, of course, entirelyredundant except when a fire occurs, or when the temperature to whichthe arrangements are subjected otherwise rises to a predetermined value.

It is a primary object of the present invention to provide an improvedform of air chamber assembly in which the ventilation air outlet duct isautomatically closed when a fire occurs in the room space or the likebelow the assembly, and in which the member for closing the ventilationair outlet duct serves, under normal operating conditions, to define anedge of the ventilation air outlet duct, the member accordingly having afunctional purpose both when the assembly is in a normal condition ofoperation and when the assembly is subjected to fire heat.

An air chamber assembly according to one aspect of the present inventioncomprises means defining a hollow air chamber casing, a first air flowduct formed in the casing for the passage of ventilation air to or fromthe interior of the casing, a support member, and spacer means whichcomprises heat-fusible means and which is so disposed in supportingrelation between the air chamber casing and the support member that anedge portion of the casing is substantially maintained at apre-determined spaced distance from the support member. Thispre-determined spaced distance defines a second air flow duct betweensaid edge portion of the air chamber casing and the support member,which communicates with a space to be ventilated for the passage ofventilation air between the interior of the air chamber casing, thecasing and said space being urged under the influence of gravity actingon the casing in the direction to cause said edge portion thereof toenter into substratially air-tight sealing contact with the supportmember on fusion of the heat-fusible means.

In certain embodiments of the invention, the spacer means consists ofthe heat-fusible means, while in other embodiments of the invention thespacer means consists of both the heatfusible means and a rigid platewhich is pivotally mounted on the casing and which is preferablyconstituted by a portion of the casing pivotally connected to theremainder of the casing, the pivotal plate presenting an edge which isdisposed in supported contact with the support member, and theheat-fusible means being secured to the pivotal plate and to theremainder of the casing to prevent pivotal movement of the pivotal plateexcept on fusion of the heat-fusible means.

In order that the invention may be more clearly understood and morereadily carried into effect the same will now, by way of example, bemore fully described with reference to the accompanying drawings inwhich FIG. 1 is a perspective view from above showing elements of a pairof air chamber assemblies according to a first embodiment of theinvention, the assemblies including adjacently disposed lighting units,the parts of elements of the assemblies being broken away for clarity;

FIG. 2- is a perspective view on an enlarged scale of one of theheat-fusible spacer means illustrated in FIG. 1;

FIG. 3 is a view, similar to FIG. 1 but on an enlarged scale, of part ofone of the air chamber assemblies illustrated in FIG. 1;

FIG. 4 is a view corresponding to FIG. 3, but showing a differentoperative condition of the assembly illustrated therein;

FIG. 5 is a view corresponding to FIG. 3, but showing a secondembodiment of the invention;

FIG. 6 is a view, corresponding to FIG. 3, but showing a thirdembodiment of the invention;

FIG. 7 is a view corresponding to FIG. 4, but showing the thirdembodiment of the invention;

FIG. 8 is a view corresponding to FIG. 3, but showing a fourthembodiment of the invention;

FIG. 9 is a sectional end view of a fifth embodiment of the invention;and

FIG. 10 is a sectional view on the line A-A in FIG. 9.

Throughout the views of the drawings, like reference numerals are usedto denote like parts.

Referring to the drawings and in particular to FIG. 1 thereof, 10denotes generally a support structure comprising a plurality ofinterconnected support members each of which is constituted by a supportbeam 11 or 12, the beams 11, 12 being suspended by means of tie members13 from, for example, a flooring support deck (not shown). The beams 11and 12 are each of inverted channel form in cross-section, and have aweb portion 14, depending substantially parallel limb portions 15, andoutwardly directed flange portions 16 projecting from the longitudinaledges of the limb portions 15 remote from the web portion 14 in a planesubstantially parallel to the plane containing the web portion 14.

The support structure constituted by the beams ll, 12 is preferably, butnot necessarily, in the form of one of the support structures disclosedin my co-pending application, Ser. No. 874,138 filed on Nov. 6, 1969.

17 denotes generally each of a plurality of means defining hollow airchamber casings, each casing 17 comprising two end walls 18 which aresubstantially identical and each of which consists of an end wallportion 19 outwardly inclined in an upward direction from a lower edgeportion 20 thereof, and side flange portions 21 which project inwardlyfrom the end wall portion 19.

The side flange portions 21 of each end wall 18 have inner edgesconstituted by upstanding ribs 22 which are secured, in

a substantially air-tight manner, to the upstanding ribs 22 of the sideflange portions 21 of the other end wall 18 of each casing 17 by means,for example, of bolts 23 shown in FIGS. 6 and 7.

The edges constituted by the upstanding ribs 22 of the side flangeportions 21 of each end wall 18 are disposed in a substantially verticalplane, so that the side flange portions 21 are of progressivelyincreasing breadth in an upward direction, the side flange portions 21of each end wall 18 being of notched form, as indicated by the referencenumeral 24, at the upper portions thereof remote from the end wallportion 19. A substantially vertical closure plate 25 is secured to theside flange portions 21 of each end wall 18 at the notched portion 24thereof, the lower edge 26 of the plate 25 being secured in asubstantially air-tight manner to the end wall portion 19. Furthermore,in each casing 17, a substantially horizontal closure plate.27 issecured, in a substantially air-tight manner, partially to the sideflange portion 21, at the notched portions 24 thereof, of each end wall18, and partially to the side flange portions 21, at the notchedportions 24 thereof, of the other end wall 18 of the casing 17. Thesesubstantially air-tight securements between the plate 27 and the sidewall flanges 21 are effected between downwardly inclined end portion 28of the plate 27 and the side flange portions 21. Each plate 27 alsopresents upstanding lateral flange portions 29 which are disposed insubstantially air-tight abutting contact with the plates 25 of the pairof end walls 18 comprising each casing 17.

The space between the pair of end walls 18 comprising each casing 17,i.e. the space which is bounded by the plate 27 and the lower parts ofthe end wall portions 19 and the side flange portions 21 of the two endwalls 18, constitutes an air chamber.

A first air flow duct is formed in each air chamber casing 17 for thepassage of ventilation air to or from the interior of the casing 17,this duct, in the embodiment of the invention illustrated in FIG. 1,being constituted by an opening 30 formed in the plate 27. Ducting 31may be operatively connected to the opening 30 in the plates 27, theducting 31 serving to convey air having the desired temperature andhumidity to the appropriate air chambers from a convenience source (notshown) thereof. In any particular installation, if certain of the airchambers are not required the closure plates 27 bounding the airchambers may be omitted, in which case these chambers serve as airreturn passages.

Spacer means comprising heat-fusible means is disposed in supportingrelation between each air chamber casing 17 and the appropriate one ofthe support beams 11 thereby to maintain an edge portion of the casing17, which edge portion is constituted by the edge portions of the endwalls 18 of the casing 17, a predetermined spaced distance above theflange portions 16 of the support beam 11, said pre-determined spaceddistance defining a second air flow duct between said edge portion ofthe casing 17 and the support beam 11, which communicates with a spaceto be ventilated for the passage of ventilation air between the interiorof the air chamber casing and said space. Except in the casehereinbefore referred to in which the air chambers serve as air returnpassages, the first air flow duct constituted by the opening 30 in theplate 27 of each casing 17 constitutes, of course, a ventilation airinlet duct to the interior of the casing 17 and the second air flow ductconstitutes a ventilation air outlet duct from the interio ofthe casing17.

With particular reference to the first embodiment of the inventionillustrated in FIGS. 1 to 4, the spacer means consists of a pair ofspaced plates 32 of heat-fusible material, the opposed side edges ofeach plate 32 being provided with grooves 33. The side flange portions21 of each end wall 18 of the casing 17 are notched at the lowerportions thereof remote from the end wall portion 19, the edges of eachside flange portion 21 of one of the end walls 18 and the edges of theadjacent side flange portion 21 of the other of the end walls 18, whichedges define said notched portions in the two side flange portions 21,together bounding a recess 34 within which the ap propriate plate 32 islocated with lateral portions of said edges disposed within the grooves33 in said plate 32. The lower edge 35 of each plate 32 bears directlyon and is in supported contact with the upper face of the web portion 14of the beam 1 1. Each plate 32 also bears directly on the casing 17.

The edge portion of the air chamber casing 17 constituted by the edgeportions 20 of the end walls 18 is thus maintained said pre-determineddistance above the outwardly directed flange portions 16 of the beam 11by means of the plates 32, the air chamber casing 17 being, however,urged, by being permitted to descend under the influence of gravityacting thereon, in the direction to cause entry of the web and limbportions 14 and 15, respectively, of the beam 11 into the recesses 34,with resultant entry of the edge portion of the air chamber casing 17which is constituted by the edge portions 20 of the end walls 18 intosubstantially air-tight sealing con tact with the flange portions 16 ofthe beam 11, on fusion of the plates 32.

As will be appreciated, the two plates 32 are disposed in the mannerhereinbefore described on opposite sides of the air chamber casing 17.

The second embodiment of the invention illustrated in FIG. 5 differsfrom that described above with reference to FIGS. 1 to 4 in that theheat-fusible spacer means is constituted, not by the plates 32, but by apair of rods 36 of heat-fusible material, one end portion 37 of each rod36 being mounted in engagement with the associated beam 11 by beingdisposed in screwthreaded engagement through an aperture 38 formed inthe web portion 14 of the beam 11. The lower end of each rod 36 ispreferably slotted as shown at 39 in FIG. 5 thereby to permit the rod 35to be rotated relative to the beam 11, by means, for example, of a screwdriver engaged with the slot 39. In this manner, the magnitude of thepredetermined distance between the edge portion of the air chambercasing 17 constituted by the edge portions 20 of the end walls 18 andthe flange portions 16 of the beam 11 may be adjusted, the upper end 40of each rod 36 being provided with a support disc which is in supportingengagement with the air chamber casing 17.

While, in the second embodiment of the invention as described above withreference to FIG. 5 of the drawings, there is, in each air chamberassembly a pair of rods 36, it will be understood that, by disposing therod 36 substantially centrally of the assembly, a single rod 36 may beused.

Referring now to the third embodiment of the invention illustrated inFIGS. 6 and 7, the spacer means comprises, in addition to heat-fusiblemeans which in this embodiment is constituted by strips 41 ofheat-fusible material, a rigid plate 42 which is pivotally mounted onthe casing 17 and which is constituted by a portion of the casing 17bounded by two slots 43, and end 44 of each of which communicates withan edge of the casing 17, and by a third slot 45 which terminatesadjacent to the other ends 46 of the slots 43. The third slot 45constitutes the pivotal axis of the portion 42 relative to the remainderof the air chamber casing 17. The heat-fusible strips 41 are secured tothe pivotal portion 42 and to the remaining portion of the air chambercasing 17 to prevent pivotal movement of the portion 42 relative to theremaining portion of the casing 17, except on fusion of the heat-fusiblemeans, each strip 41 preferably being so secured by being mounted withone end thereof disposed in secured engagement with a tooth 47 which islanced from one of the upstanding ribs 22 presented by said remainingportion of the air chamber casing 17 and the other end of said strip 41being similarly engaged by a similarly formed tooth 48 presented by aportion of the above-mentioned upstanding rib 22 which projects from thepivotal portion 42 of the casing 17. The second strip 41 is similarlysecured relative to the portions of the other upstanding nb 22, the ribs22 being, of course, discontinuous for a predetermined distance in theregion of the third slot 45 thereby to permit pivotal movement of the.

portion 42 relative to the remaining portion of the casing 17, in themanner indicated in FIG. 7, when the strips 41 are fused by beingsubjected to a temperature in excess of a pre-determined value. Suchpivotal movement of the portion 42 results in the edge portion of theair chamber casing 17 which is constituted by the edge portions 20 ofthe end walls 18 descending into substantially air-tight contact withthe flange portions 16 of the beam 1 1 as illustrated in FIG. 7, saidedge portion of the casing 17 normally being maintained thepre-determined distance from the flange portions 16 of the beam 11 bythe supporting contact between the web portion 14 of the beam 11 and thelower edges 49 of the pivotal portions 42.

With reference to the embodiment of the invention illustrated in FIG. 8,this embodiment differs from that illustrated in FIGS. 1 to 4 in thatinstead of the plates 32 there is provided a pair of spaced hollowbodies 50 which are preferably of trapezoidal form in cross-section, thelower surface of each body 50 being in supported contact with the webportion 14 of the associated beam 11, and the upper surface of each body50 presenting two spaced, parallel flanges 51 within which one limb 52of a substantially L-shaped metal bracket member 53, the other limb 54of which is secured as by bolts 55 to the air chamber casing 17, isdisposed. As in the case of the embodiment illustrated in FIGS. 6 and 7,the fourth embodiment illustrated in FIG. 8 incorporates rigid plates 42each of which is pivotally mounted on the casing 17, and preferablycomprises a portion of the casing 17 bounded by slots 43 and 45, theportions 42 presenting lower edges 49 disposed substantially in contactwith the web portion 14 of the beam 11, and being pivotally mountedrelative to the remaining portion of the air chamber casing 17 thereby,on fusion of the bodies 50, to permit the edge portion of the casing 17which is constituted by the edge portions 20 of the end walls 18 todescend under gravity into substantially air-tight contact with theflange portions 16 of the beam 11.

While, in the fourth embodiment of the invention as described above withreference to FIG. 8 of the drawings, there is, in each air chamberassembly a pair of bodies 50, it will be understood that by disposingthe body 50 substantially centrally of the assembly, a single body 50may be used. Finally, the fifth embodiment of the invention illustratedin FIGS. 9 and 10, differs from the first embodiment described abovewith reference to FIGS. 1 to 4 merely in that the heatfusible spacermeans comprises a pair of spaced, hollow bodies 56 which are disposedbetween the flange portions 16 of the associated beam 11 and the edgeportions 20 of the end walls 18 of the casing 17 thereby to maintain theedge portion of the casing 17 which is constituted by said edge portions20 said pre-determined distance from the flange portions 16 of the beam11. Each of the bodies 56 is provided with a longitudinally extendingnotch 57 within which the edge portion 20 of the associated end wall 18of the casing 17 is disposed as shown in FIG. 10, the bodies 56 beingdisposed at the ends of the ventilation air outlet slot and beingpartially of tapered form as shown at 58 thereby to ensure that theventilation air outlet slot is of substantially rectangular form. Inthis manner, difficulties which may arise in ensuring that the desiredair flow pattern through the ventilation air outlet slots are achieved,these difficulties resulting from the tapered form of the end portionsof the slots, are substantially overcome. In

the third embodiment of the invention shown in FIGS. 6 and 7 of thedrawings, the lower edge portions of the strips 41 are in tension, andthe upper edge portions of the strips 41 are in compression. Referringto the remaining embodiments of the invention as hereinbefore describedwith reference to the drawings, it will be noted that the heat-fusiblemeans constituted by the plates 32 of the embodiment shown in FIG. 1 to4, the rods 36 of the embodiment shown in FIG. 5, the bodies 50 of theembodiment shown in FIG. 8, and the bodies 56 of the embodiment shown inFIGS. 9 and are under compression and are not under tensile stressing,the heat-fusible means constituted by, for example, the plates 32 shownin FIG. 1 being, however, also under shear stressing.

With particular reference again to FIG. 1 of the drawings, 59 denotesgenerally each of two lighting unit structures, only the forward portionof the rear lighting unit structure 59 being illustrated.

The lighting unit structure 59 are substantially identical and eachcomprises spaced end walls one of which is constituted by one of the endwalls 18 of one of the air chamber casings 17 and the other of which isconstituted by one of the end walls 18 of the adjacent air chambercasing 17. Each lighting unit structure 59 also comprises a member 60which constitutes part of a lighting element and which has a web portion61, a pair of opposed, parallel limb portions 62 and a pair of outwardlyinclined flange portions 63, the portions 63 being connected to the limbportions 62 through ledges 64.

A closure plate (not shown) is secured to the undersides of the ledges64 of each member 60, a lamp (not shown), which is preferably in theform of a fluorescent lighting lamp, being mounted on the underside ofthe closure plate. The closure plate and the lamp constitute furtherparts of the above-mentioned lighting element. The space bounded by theweb and limb portions 61, 62 of each member 60 and by the associatedclosure plate operatively contains the ballast and other auziliarycircuit elements of the lighting element. These circuit elements may beof conventional form. A translucent lens (not shown) is mounted on eachmember. 60 and is operatively retained in position by means of inwardlydirected edge portions of the inclined flange portions 63, each endportion of the translucent lens being disposed through a correspondinglyformed opening in the end wall portion 19 of the appropriate end wall 18with the lens mounted on the lower edge 26 of the plate 25 which issecured to said end wall portion 19.

In each structure 59 the member 60 rigidly interconnects the associatedend walls 18 by means, for example, of bolts 65 between the inclinedflange portions 63 of the member 60 and the side flange portions 21 ofthe end walls 18.

Heat insulation panels 66 are each mounted with the lower edge portionsthereof in supported engagement with the appropriate flange portion 16of one of the beams 12 and with the upper edge portion thereof insupported engagement with the appropriate inclined flange portion 63 ofthe member 60 of the appropriate structure 59. The lower faces of thepanels 66 are preferably formed of a light reflecting material therebyto reflect the light from the fluorescent lighting lamp of theassociated lighting element into the room space of the like disposedtherebelow.

The purpose of the notched portions 24 in the side flange portions 21 ofthe end walls 18, and of the associated closure plates 25 and 27, is topermit increased flexibility in the manner in which air chamberassemblies and'the lighting unit structures 59 may be used. Thus, forexample, where it is desired to use air chamber assemblies and thestructures 59 in such a manner that the members 60 of the structures 59are disposed substantially at right angles to horizontal beams orgirders, such as girders supporting the ceiling, and where it isrequired that the level of the upper faces of the members 60 be abovethe lower faces of these beams or girders, the beams or girders, anddisposed through the spaces bounded by the plates 25 and 27 of the airchamber casings 17. Where beams or girders are so disposed it is not, ofcourse, possible for the 4 associated air chambers to be used, or ifthey are to be used alternative arrangements (not shown) to thatconstituted by the opening 30 in the plate 27 will be required forsupplying the air to the chambers. It is to be emphasized that theabovedescribed manner of using the air chamber assemblies and thelighting unit structures 59 in which beams or girders are disposedthrough the spaces bounded by the plates 25 and 27 of the casings 17 ismerely one example of the ways in which the assemblies and structures 59may be used where the notched portions 24 in the side flange portions 21of the end walls 18, or notched portions of different forms, areprovided.

Furthermore,-it is, of course, to be understood that where notchedportions in the side flange portions 21 of each end wall 18 are notrequired, such as where the above problem resulting from the presence ofhorizontal beams or girders does not arise, the notched portions 24 inthe side flange portions 21 of each end wall 18, and the associatedclosure plates 25 and 27, may be omitted, and that these are not,therefore, essential features of the invention.

While as described above with reference to FIG. 1 the end walls 18 ofeach air chamber casing 17 each also constitutes an end wall of one ofthe lighting unit structures 59, as in the case of the invention formingthe subject of my co-pending application, Ser. No. 874,140 filed on Nov.6, 1969, it is to be understood that in the present invention the airchamber casing 17 may be quite separate and distinct from any lightingunit structures between which the casing 17 is operatively disposed.

The present invention thus provides an air chamber assembly in which thepre-determined space between the edge portion of the casing 17constituted by the edge portions of the end walls 18, and the flangeportions 16 of the associated beam 11 is automatically closed when atire occurs in the room space or the like below the assembly, the endflange portions 19 of the end walls 18 which close this space serving,of course, to define an edge of the space under normal operatingconditions. The end flange portions 19 accordingly have a functionalpurpose both when the assembly is in a normal condition of operation andwhen the assembly is subjected to fire heat.

What 1 claim as my invention is:

1. Air chamber assembly comprising means defining a hollow air chambercasing, a first air flow duct formed in the easing for the passage ofventilation air to or from the interior of the casing, a support member,and spacer means which comprises heat-fusible means and which isdisposed in supporting relation between the air chamber casing and thesupport member thereby to maintain an edge portion of the air chambercasing a pre-determined spaced distance from the support member, saidpre-determined spaced distance defining a second air flow ducttherebetween communicating with a space to be ventilated for the passageof ventilation air between the interior of the air chamber casing andsaid space, and the casing being urged under the influence of gravityacting on the casing in the direction to cause said edge portion thereofto enter into substantially air-tight sealing contact with the supportmember on fusion of the heat-fusible means.

2. Air chamber assembly comprising means defining a hollow air chambercasing, a first air flow duct formed in the casing for the passage ofventilation air to or from the interior of the casing, a support member,and spacer means which consists of heat-fusible means disposed insupporting relation between the support member and the air chambercasing with the heat-fusible means bearing directly on the supportmember and on the air chamber casing, thereby to maintain an edgeportion of the air chamber casing a predetermined spaced distance fromthe support member, said predetermined spaced distance defining a secondair flow duct therebetween communicating with a space to be ventilatedfor the passage of ventilation air between the interior of the airchamber casing and said space, and the casing being urged in thedirection to cause said edge portion thereof to enter into substantiallyair-tight sealing contact with the support member of fusion of theheat-fusible means.

3. Air chamber assembly according to claim 2, wherein the support membercomprises a beam of inverted channel form in cross-section, the beamhaving a web portion, depending substantially parallel limb portions,and outwardly directed flange portions projecting from the longitudinaledges of the limb portions of the beam remote from the web portion in aplane substantially parallel to the plane containing the web portion;and the heat-fusible means comprises a pair of spaced plates ofheat-fusible material, the opposed side edges of each of which aregrooved with the lateral edge portions of the cas ing bounding a recessformed therein disposed within the grooves, the lower edge of each platebeing in supported contact with the upper face of the web portion of thebeam thereby to maintain said edge portion of the air chamber casingsaid pre-determined distance above the outwardly directed flangeportions of the beam, while permitting the air chamber casing to descentunder gravity with resultant entry of the web and limb portions of thebeam into the recesses formed in the casing and entry of said edgeportion of the casing into substantially air-tight sealing contact withthe flange portions of the beam, on fusion of the plates.

4. Air chamber assembly according to claim 1, wherein the heat-fusiblemeans comprises at least one rod of heat-fusible material, one endportion of the rod being mounted in engagement with the support memberand the other end of the rod supporting the air chamber casing.

5. Air chamber assembly according to claim 4,,wherein said one endportion of the heat-fusible rod is in screw-threaded engagement with anaperture formed in the support member, thereby permitting variation inthe magnitude of said predetermined distance between said edge portionof the air chamber casing and the support member.

6. Air chamber assembly according to claim 1, including two adjacentlydisposed lighting unit structures each of which comprises spaced endwalls and a member which rigidly interconnects the end walls and whichis adapted to support at least one lamp, each end wall including an endwall portion and said flange portions which project from the inner wallportion, and which present edges, and the adjacent end walls of the twoadjacently disposed lighting unit structures together constituting theair chamber casing, with the edges of the side flange portions of saidadjacent end walls being secured together in a substantially air-tightmanner.

7. Air chamber assembly according to claim 1, wherein the heat-fusiblemeans comprises a body the upper surface of which presents two spaced,parallel flanges, a bracket member presented by the air chamber casingbeing disposed between said spaced, parallel flanges in supportedcontact with the body. I

8. Air chamber assembly according to claim 7, wherein a rigid plate ispivotally mounted on the air chamber casing, said pivotal platepresenting an edge which is disposed substantially in contact with theweb portion of the support beam.

9. Air chamber assembly according to claim 8, wherein the pivotal plateis constituted by a portion of the air chamber casing bounded by twoslots, one end of each of which communicates with an edge of the casing,and by a third slot which terminates adjacent to the other ends of saidtwo slots, the third slot constituting the axis about which the pivotalplate may move relative to the casing.

10. Air chamber assembly according to claim 1, wherein the spacer meansfurther comprises a rigid plate which is pivotally mounted on the airchamber casing, said pivotal plate presenting an edge which is disposedin supported contact with the support member thereby to maintain saidedge portion of the casing said pre-determined distance from the supportmember and the heat-fusible means being secured to the pivotal plate andto the casing to prevent pivotal movement of the pivotal plate relativeto the casing except on fusion of the heat-fusible means.

11. Air chamber assembly according to claim 10, wherein the pivotalplate is constituted by a portion of the air chamber casing bounded bytwo slots one end of each of which communicates with an edge of thecasing, and by a third slot which terminates adjacent to the other endsof said two slots, the third slot constituting the axis about which thepivotal plate may move relative to the casing.

12. Air chamber assembly comprising a hollow air chamber casing, a firstair flow duct formed in the casing for the passage of ventilation air toor from the interior of the casing, a support beam of inverted channelform in cross-section, the beam having a web portion, dependingsubstantially parallel limb portions, and outwardly directed flangeportions projecting from the longitudinal edges of the limb portions ofthe beam remote from the web portion in a plane substantially parallelto the plane containing the web portion, and heat-fusible spacer meansdisposed between the web portion of the support beam and the air chambercasing thereby to maintain an edge portion of the air chamber casing apre-determined spaced distance from the flange portions of the supportbeam, said pre-determined spaced distance constituting a second air flowduct for the passage of ventilation air from or to, respectively, theinterior of the air chamber casing, and the casing being urged undergravity in the downward direction to cause said edge portion thereof toenter into substantially air-tight sealing contact with the flangeportions of the support beam on fusion of the spacer means 13. Airchamber assembly according to claim 12, wherein the spacer meanscomprises a hollow body the upper surface of which presents two spaced,parallel flanges, a bracket member presented by the air chamber casingbeing disposed between said spaced, parallel flanges in supportedcontact with the hollow body 14. Air chamber assembly according to claim12, wherein a rigid plate is pivotally mounted mounted on the airchamber casing, said pivotal plate presenting an edge which is disposedsubstantially in contact with the web portion of the support beam.

15. Air chamber assembly according to claim 14, wherein the pivotalplate is constituted by a portion of the air chamber casing bounded bytwo slots, one end of each of which communicates with an edge of thecasing, and by a third slot which terminates adjacent to the other endsof said two slots, the third slot constituting the axis about which thepivotal plate may move relative to the casing.

16. Air chamber assembly comprising means defining a hollow air chambercasing, a first air flow duct formed in the casing for the passage ofventilation air to or from the interior of the casing, a support member,and spacer means which comprises heat-fusible means and which isdisposed in supporting relation between the air chamber casing and thesupport member with the heat-fusible means under compression thereby tomaintain an edge portion of the air chamber casing a pre-determinedspaced distance from the support member, said pre-determined spaceddistance defining a second air flow duct therebetween communicating witha space to be ventilated for the passage of ventilation air between theinterior of the air chamber casing and said space, and the casing beingurged in the direction to cause said edge portion thereof to enter intosubstantially air-tight sealing contact with the support member onfusion of the heat-fusible means.

17. Air chamber assembly comprising means defining a hollow air chambercasing, a first air flow duct formed in the casing for the passage ofventilation air to or from the interior of the casing, a support member,and spacer means which comprises heat-fusible means and which isdisposed is supporting relation between the air chamber casing and thesupport member, with the heat-fusible means not under tensile stressing,thereby to maintain an edge portion of the air chamber casing apre-determined spaced distance from the support member, saidpre-determined spaced distance defining a second air flow ducttherebetween communicating with a space to be ventilated for the passageof ventilation air between the interior of the air chamber casing andsaid space. and the casing being urged in the direction to cause saidedge portion thereof to enter into substantially air-tight sealingcontact with the support member on fusion of the heat-fusible means.

1. Air chamber assembly comprising means defining a hollow air chambercasing, a first air flow duct formed in the casing for the passage ofventilation air to or from the interior of the casing, a support member,and spacer means which comprises heatfusible means and which is disposedin supporting relation between the air chamber casing and the supportmember thereby to maintain an edge portion of the air chamber casing apredetermined spaced distance from the support member, saidpredetermined spaced distance defining a second air flow ducttherebetween communicating with a space to be ventilated for the passageof ventilation air between the interior of the air chamber casing andsaid space, and the casing being urged under the influence of gravityacting on the casing in the direction to cause said edge portion thereofto enter into substantially airtight sealing contact with the supportmember on fusion of the heat-fusible means.
 2. Air chamber assemblycomprising means defining a hollow air chamber casing, a first air flowduct formed in the casing for the passage of ventilation air to or fromthe interior of the casing, a support member, and spacer means whichconsists of heat-fusible means disposed in supporting relation betweenthe support member and the air chamber casing with the heat-fusiblemeans bearing directly on the support member and on the air chambercasing, thereby to maintain an edge portion of the air chamber casing apredetermined spaced distance from the support member, saidpredetermined spaced distance defining a second air flow ducttherebetween communicating with a space to be ventilated for the passageof ventilation air between the interior of the air chamber casing andsaid space, and the casing being urged in the direction to cause saidedge portion thereof to enter into substantially air-tight sealingcontact with the support member of fusion of the heat-fusible means. 3.Air chamber assembly according to claim 2, wherein the support Membercomprises a beam of inverted channel form in cross-section, the beamhaving a web portion, depending substantially parallel limb portions,and outwardly directed flange portions projecting from the longitudinaledges of the limb portions of the beam remote from the web portion in aplane substantially parallel to the plane containing the web portion;and the heat-fusible means comprises a pair of spaced plates ofheat-fusible material, the opposed side edges of each of which aregrooved with the lateral edge portions of the casing bounding a recessformed therein disposed within the grooves, the lower edge of each platebeing in supported contact with the upper face of the web portion of thebeam thereby to maintain said edge portion of the air chamber casingsaid pre-determined distance above the outwardly directed flangeportions of the beam, while permitting the air chamber casing to descentunder gravity with resultant entry of the web and limb portions of thebeam into the recesses formed in the casing and entry of said edgeportion of the casing into substantially air-tight sealing contact withthe flange portions of the beam, on fusion of the plates.
 4. Air chamberassembly according to claim 1, wherein the heat-fusible means comprisesat least one rod of heat-fusible material, one end portion of the rodbeing mounted in engagement with the support member and the other end ofthe rod supporting the air chamber casing.
 5. Air chamber assemblyaccording to claim 4, wherein said one end portion of the heat-fusiblerod is in screw-threaded engagement with an aperture formed in thesupport member, thereby permitting variation in the magnitude of saidpre-determined distance between said edge portion of the air chambercasing and the support member.
 6. Air chamber assembly according toclaim 1, including two adjacently disposed lighting unit structures eachof which comprises spaced end walls and a member which rigidlyinterconnects the end walls and which is adapted to support at least onelamp, each end wall including an end wall portion and said flangeportions which project from the inner wall portion, and which presentedges, and the adjacent end walls of the two adjacently disposedlighting unit structures together constituting the air chamber casing,with the edges of the side flange portions of said adjacent end wallsbeing secured together in a substantially air-tight manner.
 7. Airchamber assembly according to claim 1, wherein the heat-fusible meanscomprises a body the upper surface of which presents two spaced,parallel flanges, a bracket member presented by the air chamber casingbeing disposed between said spaced, parallel flanges in supportedcontact with the body.
 8. Air chamber assembly according to claim 7,wherein a rigid plate is pivotally mounted on the air chamber casing,said pivotal plate presenting an edge which is disposed substantially incontact with the web portion of the support beam.
 9. Air chamberassembly according to claim 8, wherein the pivotal plate is constitutedby a portion of the air chamber casing bounded by two slots, one end ofeach of which communicates with an edge of the casing, and by a thirdslot which terminates adjacent to the other ends of said two slots, thethird slot constituting the axis about which the pivotal plate may moverelative to the casing.
 10. Air chamber assembly according to claim 1,wherein the spacer means further comprises a rigid plate which ispivotally mounted on the air chamber casing, said pivotal platepresenting an edge which is disposed in supported contact with thesupport member thereby to maintain said edge portion of the casing saidpre-determined distance from the support member and the heat-fusiblemeans being secured to the pivotal plate and to the casing to preventpivotal movement of the pivotal plate relative to the casing except onfusion of the heat-fusible means.
 11. Air chamber assembly according toclaim 10, wherein the pivotal plate is constituted by a portIon of theair chamber casing bounded by two slots one end of each of whichcommunicates with an edge of the casing, and by a third slot whichterminates adjacent to the other ends of said two slots, the third slotconstituting the axis about which the pivotal plate may move relative tothe casing.
 12. Air chamber assembly comprising a hollow air chambercasing, a first air flow duct formed in the casing for the passage ofventilation air to or from the interior of the casing, a support beam ofinverted channel form in cross-section, the beam having a web portion,depending substantially parallel limb portions, and outwardly directedflange portions projecting from the longitudinal edges of the limbportions of the beam remote from the web portion in a planesubstantially parallel to the plane containing the web portion, andheat-fusible spacer means disposed between the web portion of thesupport beam and the air chamber casing thereby to maintain an edgeportion of the air chamber casing a pre-determined spaced distance fromthe flange portions of the support beam, said pre-determined spaceddistance constituting a second air flow duct for the passage ofventilation air from or to, respectively, the interior of the airchamber casing, and the casing being urged under gravity in the downwarddirection to cause said edge portion thereof to enter into substantiallyair-tight sealing contact with the flange portions of the support beamon fusion of the spacer means.
 13. Air chamber assembly according toclaim 12, wherein the spacer means comprises a hollow body the uppersurface of which presents two spaced, parallel flanges, a bracket memberpresented by the air chamber casing being disposed between said spaced,parallel flanges in supported contact with the hollow body.
 14. Airchamber assembly according to claim 12, wherein a rigid plate ispivotally mounted mounted on the air chamber casing, said pivotal platepresenting an edge which is disposed substantially in contact with theweb portion of the support beam.
 15. Air chamber assembly according toclaim 14, wherein the pivotal plate is constituted by a portion of theair chamber casing bounded by two slots, one end of each of whichcommunicates with an edge of the casing, and by a third slot whichterminates adjacent to the other ends of said two slots, the third slotconstituting the axis about which the pivotal plate may move relative tothe casing.
 16. Air chamber assembly comprising means defining a hollowair chamber casing, a first air flow duct formed in the casing for thepassage of ventilation air to or from the interior of the casing, asupport member, and spacer means which comprises heat-fusible means andwhich is disposed in supporting relation between the air chamber casingand the support member with the heat-fusible means under compressionthereby to maintain an edge portion of the air chamber casing apre-determined spaced distance from the support member, saidpre-determined spaced distance defining a second air flow ducttherebetween communicating with a space to be ventilated for the passageof ventilation air between the interior of the air chamber casing andsaid space, and the casing being urged in the direction to cause saidedge portion thereof to enter into substantially air-tight sealingcontact with the support member on fusion of the heat-fusible means. 17.Air chamber assembly comprising means defining a hollow air chambercasing, a first air flow duct formed in the casing for the passage ofventilation air to or from the interior of the casing, a support member,and spacer means which comprises heat-fusible means and which isdisposed is supporting relation between the air chamber casing and thesupport member, with the heat-fusible means not under tensile stressing,thereby to maintain an edge portion of the air chamber casing apre-determined spaced distance from the support member, saidpre-determined spaced distance defining a second air flow ducttherebetween communicAting with a space to be ventilated for the passageof ventilation air between the interior of the air chamber casing andsaid space, and the casing being urged in the direction to cause saidedge portion thereof to enter into substantially air-tight sealingcontact with the support member on fusion of the heat-fusible means.